Webb confirms we’re looking at some of the Universe’s earliest galaxies
Enlarge / Galaxies that appear to be similar in age to the ones described here. (credit: NASA, ESA, CSA, Tommaso Treu, Zolt G. Levay)
One of the goals of the Webb Space Telescope was imaging the earliest galaxies, giving us a new window into how our Universe evolved between the dense, hot material from the Big Bang and its star- and structure-filled present. And, almost as soon as the data started pouring in, things have looked very promising, with strong indications that we were picking up galaxies as they appeared only a few hundred million years after the Big Bang.
But a few uncertainties remained, as unusual conditions could potentially cause a much more recent galaxy to have features that make it look much older. That may be the case with a galaxy that would otherwise be the oldest ever detected.
On Tuesday, two papers were released that put the issue to rest, providing a full spectrum of four early galaxies and showing that they all clearly date from just a few hundred million years after the Big Bang. Imaging of the same galaxies shows that they're full of young stars that lack most of the heavier elements seen in today's Universe.